Field of the Invention
The invention concerns a method for communicating between a first communication device of a magnetic resonance device and a second communication device of the magnetic resonance device, particularly one that is mobile and on the patient side. The invention also relates to such a magnetic resonance apparatus.
Description of the Prior Art and Related Subject Matter
Magnetic resonance devices are widely known in the prior art and are now established as medical imaging devices. For the purpose of imaging, the patient is introduced with a patient couch into a usually cylindrical patient retainer inside a main magnetic unit. The magnetic resonance device is located in a shielded enclosure, which is usually vacated by the operating personnel during the imaging process. A significant amount of noise is generated in the area of the magnetic resonance device during the imaging process. Moreover, the patient retainer of the magnetic resonance device is usually relatively narrow. It is therefore expedient to implement a facility for communicating with the patient, particularly to enable anxious patients to be reassured, and so that instructions can be conveyed to the patient.
Pneumatically operated communication systems have been proposed for this purpose, in which acoustic information is transferred to a patient headset by air pressure modulation. For the return communication it has been proposed, for example, for the patient to use a pneumatically operated call ball; in addition or alternately, microphones may be arranged at the edge of the patient receptacle.
While a call ball is often straightforward to implement, the pneumatic transmission of acoustic information by air pressure modulation requires a complex arrangement of compressed-air hoses, which complicates the layout and operation of the magnetic resonance device. A further disadvantage of transmitting useful signals pneumatically is the poor transmission quality that is achieved.
In the post-published German patent application DE 10 2014 203 368.3 a communication method is proposed that uses radio signals, wherein a carrier signal with a first frequency is emitted by a first communication device of the magnetic resonance apparatus, which is arranged on the basic field magnet side, and this first carrier signal is received on the patient side. There, a second carrier signal is generated with a second frequency, which is different from the first frequency, with a pre-set rational frequency ratio to the first frequency and with a pre-set phase position to the phase of the first carrier signal, onto which the useful signal is modulated, so that the transmit signal thus produced can be returned to the first communication device. In other words, in the second, patient-side communication device, the principle of a phase-locked transponder is used, but the phase-locked transponder signal is not transmitted directly, but is additionally modulated by a useful signal. By continuous transmission of the first carrier signal and of the transmit signal, it is possible for faults in the connection to be detected immediately. Embodiments of the communication method described therein also permit bidirectional communication. The use of radio does however cause problems with regard to approval and/or possible interference/distortions in the magnetic resonance device.